Wednesday, February 4, 2009

Octane Rating

Have you ever found yourself wondering "What's up with the octane ratings here?"

When I first got here, I really didn't know which gas to buy. The Shell station next to my house has unleaded with 91 and 95 octane. 91 octane for unleaded seems a lot higher than gas in the States. So does that mean regular gas here has a a higher octane rating than premium gas in the US?

No.

If you’re interested in the science check out the Wikipedia article.

Here’s the Reader’s Digest version: There are two methods to calculate Octane rating in gasoline: Motor Octane Number (MON) and Research Octane Number (RON).

What’s more important than what they are, is where they are used. In the states, the number on the pump is the average of these two ratings. Here in Poland (and much of the rest of the world) they just use the RON (or the larger) number.

Why do you care? If your car is American, check out the owner’s manual. It will tell you the minimum octane rating (most likely the average of RON and MON). For example my '07 Dodge Grand Caravan lists the rating at 87 Octane. Great - If I was in the States. For some reason the Dodge's owner's manual does not list the international RON rating. Probably because it would confuse people.

I dug through the Owner's manuals on my motorcycles and found a much clearer answer:

My '09 Harley takes the 95 Octane gas here; the equivalent to 91 octane on a Stateside pump.
My '91 Suzuki takes 91 Octane here; the equivalent of 87 Octane Stateside.

So that's how we roll now. For the Dodge and the Suzuki we get the 91 Octane, but not lower. Getting a lower octane is not so much a problem here in Poland, but be aware when you go to Germany because they do have the 90 RON there. That's probably not what you want to put in your car.

For the Harley - She takes premium - which as long as I get the 95 RON, I'm good.

Most mechanics will agree that unless your owner's manual specifically says otherwise - there is usually no need to put in more expensive gas than necessary. Certainly not on a regular basis.

Confused? Ask the attendant - Even if it's not marked - they can tell you what the octane rating is. It does help to be able to count to ten in Polish...

So the next time you're at the pump - make sure you're putting in only what you need. It could save you several bucks each time you go to the pump. Over a year (depending on the exchange rate) that could add up to some serious zlotys...

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